Osteoarthritis (OA) is a degenerative joint disease that occurs due to gradual wear and tear of cartilage tissue at the ends of joint forming bones. Lack of blood vessels limits selfhealing capability of cartilage and makes osteoarthritis an irreversible condition. Early diagnosis of OA has been a challenge since cartilage does not contain nerves and pain can only be realized when the bone ends at the joint rub against each other. OA can severely impair cartilage’s load bearing capacity by changing its material properties well before the onset of structural damage. The goal of this thesis is to understand function-properties correlation in osteoarthritic cartilage and develop a protocol to identify and measure critical mechanical properties that can be associated with cartilage health.

Biphasic poro-visco-elastic constitutive material model (BPVE) was chosen to capture both fluid flow dependent and independent relaxation behaviour of cartilage under stress relaxation type indentation. A finite element model based on BPVE formulation was developed in ABAQUS® to run the indentation tests in-silico. The BPVE model was explored for the sensitivity to Young’s modulus, Poisson’s ratio, permeability and Prony series coefficients. Then numerical output reaction force versus time curves were fit with previously collected experimental force relaxation plots obtained from indentation tests to extract the material properties. Osteoarthritic model of cartilage specimen was created by injecting trypsin at select site on the lateral plateau of bovine tibia. The protocol developed in this thesis was able to successfully measure the spatial and temporal variances of mechanical properties in the specimen with response to trypsin digestion, and the areas of degeneration were found to be characterized by rapid change in permeability and Prony series coefficients. These findings suggest that cartilage degradation reduces the intrinsic viscoelastic properties of the tissue’s solid phase in addition to impairing its capacity to offer frictional drag to the interstitial fluid flow (permeability). These changes were identified before structural alterations were present.